Excellent choice. Unfortunately, we have already been there. It may warrant a second visit though. Thanks for the suggestion.
Do you have any interest in the history of technology, particularly electricity and communications? There's a fabulous museum in Bellingham, about 60 miles north of Seattle, which I visited a few years ago: SPARK Museum of Electrical Invention in Bellingham, WA The guy who owns it, John Jenkins, made a lot of money at Microsoft and turned his lifetime hobby with its extensive collection of very rare items into the museum. He has original electrical equipment from as early as the late 1700s, the very beginnings of the study of the field. The town also has some good restaurants and a couple of large used-book stores.